1. Field of the Invention
The present invention generally pertains to cordless data transmission systems. In particular, the present invention pertains to data transmission in cordless data transmission systems.
2. Discussion of the Related Art
Data telecommunication (datel) is the mutual sending and receiving of data or data signals, such as packet data, between a data terminal equipment and a remote data terminal equipment via a telecommunication network, for example a public telecommunication network, such as ISDN, PSTN, etc. The term data terminal equipment refers to personal computers, data terminals, DP systems etc. The term remote data terminal equipment refers to personal computers, data terminals, DP systems etc. So that the data or data signals sent by the data terminal equipment can be transmitted via the telecommunication network, a network facility, so-called data communication equipment, is provided between the data terminal equipment and the telecommunication network. Apart from the PC card, previously known as a PCMCIA card, the most widely used data communication equipment is the modem.
The modem is an electrical data communication equipment operating on the basis of the carrier-current method for use on analogue transmission paths of limited bandwidth—e.g. telecommunication lines, such as a/b circuit pair, ISDN-S0-BUS etc., of a telecommunication network. Modems convert and transmit digital data signals into analogue data signals and vice-versa. Furthermore, a multiplicity of methods of the V series standardized by the International Telecommunication Union-Telecommunication Standards (ITU-T)—are implemented in modems.
Discussion of the DECT (Digital Enhanced Cordless Telecommunications) standards is given at pages 1-12 and in the summary in Nachrichtentechnik Elektronik 42, January/February 1992, No. 1, Berlin, Del.; in U. Pilger “Struktur des DECT-Standards” (“Structure of the DECT Standard”), pages 23 to 29, in conjunction with ETSI publication ETS 300175-1 . . . 9, October 1992; the text of a lecture by A. Elberse, M. Barry and G. Fleming entitled “DECT Data Services—DECT in Fixed and Mobile Networks”, on Jun. 17-18, 1996, at the Sofitel Hotel in Paris; the publication by S. Althammer and D. Brückmann entitled “Hochoptimierte IC's für DECT-Schnurlostelefone” (“Highly Optimized ICs for Cordless DECT Telephones”); and in the DECT publication of the DECT Forum, February 1997, pages 1 to 16.
Discussion of the GSM (Groupe Spéciale Mobile or Global System for Mobile Communication) standard is given in Informatik Spektrum 14, June 1991, No. 3, Berlin, Del.; in A. Mann's “Der GSM-Standard—Grundlage für digitale europäische Mobilfunknetze” (“The GSM Standard—Basis for Digital European Mobile Radio Networks”), pages 137 to 152, in conjunction with the publication Telekom Praxis April, 1993; and in P. Smolka's “GSM-Funkschnittstelle—Elemente und Funktionen” (“The GSM Radio Interface—Elements and Functions”), pages 17 to 24.
Discussion of the Universal Mobile Telecommunications System (UMTS) is given in Funkschau June 1998; in R. Sietmann “Ringen um die UMTS-Schnittstelle” (“Fighting for the UMTS Interface”), pages 76 to 81; in WACS or PACS, IS-54, IS-95, PHS, PDC etc.; IEEE Communications Magazine, January 1995, pages 50 to 57; and in D. D. Falconer, et al., “Time Division Multiple Access Methods for Wireless Personal Communications.”
Additional discussion is given in the publication “Vortrag von A. Elberse, M. Barry, G. Fleming zum Thema; in the printed documents Components 31 (1993), Vol. 6, pages 215 to 218; and in WO 96/38991.
The basis of the present invention involves controlling, in a cordless V.24 data transmission system operated between a data terminal equipment and a data communication equipment for the purpose of data telecommunication, the reactivating and deactivating of an auto-bauding function in such a manner that a reliable implementation of the auto-bauding function becomes possible. According to the method of the present invention, there is no risk that the user data transmission, until it is deactivated, is corrupted by the auto-bauding function which is activated until then.